The Parallel Alignment Of Platy Grains ? Geology Chapter 7 Flashcards

Takes place when a protolith endures a rise/fall in temperature and/or pressure, undergoes compression and shear (stress), or reacts with very hot water.

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Parallel alignment of platy minerals, and/or the presence of alternating light and dark colored minerals.
Recrystallization, Phase Change, Metamorphic Reaction (neocrystallization), Pressure solution & Plastic Deformation
Slate (Finest Grained foliated metamorphic rock), Phyllite (Fine Grained), Metaconglomerate, Schist (Medium-Coarse Grained) , Gneiss (Alternating dark & light colored minerals-giving a striped appearance), Migmatite
Minerals that recrystallize or grow during metamorphism but have no foliation. Lack of foliation means either that metamorphism occurred in the absence of compression and shear or that most new crystals are equant.
The line on a map along which an index mineral first appears. All points along line have approx. the same metamorphic grade.
Regions between two isograds. Zones are named after an index mineral that wasn”t present in the previous, lower grade zone.
Include several different kinds of rocks that differ form each other in terms of chemical composition and mineral content, but all formed under roughly the same temperature & pressure conditions.
Metamorphism that occurs during mountain building and during subduction, where sea floor sediment is carried to the base of an accretionary prism. Takes the rock to the heat.

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Develops in response to heat without change in pressure and without differential stress. (Think of pottery and how it goes from wet & soft to hard) The extent of transformation depends on the grade of metamorphic rock/temperature. Takes the heat to the rock.
(Thermal Metamorphism) To emphasize that it develops next to an intrusion. Takes place anywhere the intrusion of plutons occurs- at convergent plate boundaries in rifts and during mountain building that takes place when continents collide.
Minerals rotate into favorable orientationsSome minerals dissolve and new minerals crystallize in favorable positions.
Metamorphism that occurs as a consequence of shearing alone, with no change in temperature or pressure.
Layering formed as a consequence of the alignment of mineral grains, or of compositional banding in a metamorphic rock.
A compositionally banded metamorphic rock typically composed of alternating dark- and light-colored layers.

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Rock that undergoes metamorphism simply because of a change in temperature, without being subjected to differential stress.




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